Abstract

An automated laser-beam positioning system has been developed and applied to long-path (700 m) monitoring of atmospheric aerosols. The system is based on a piezoelectric-driven mirror mount whose vertical and horizontal positioning is precisely controlled so as to maximize the return beam intensity. By optimizing the direction of the transmitted beam every 5–10 min, the change in aerosolextinction can be measured to an accuracy of better than without interference from beam displacement due to the temperature change. This positioning method allows one to use relatively small detectors and optical components which are easier to operate and maintain when compared with the previous method for the long-path measurement.